1. Field of the Invention
The field of the present invention is generally related to ophthalmic laser systems and more particularly, to apparatus, systems, and methods of iris-pupil contrast enhancement in ophthalmic laser surgery.
2. Background
In current ophthalmic laser surgery procedures, a combination of optical microscopes and directed light from a light source is used to view the patient's eye. These optical microscopes typically use refractive lenses to focus light into the viewer's eye or another light detector. More recently, image sensors, such as photoelectric light sensor arrays using charge coupled devices (CCDs) (e.g., complementary metal oxide semiconductor (CMOS) sensors), have been developed and capture digital images. When implemented as a digital camera, the digital camera can capture images of the patient's eye.
Centration or alignment of the laser and laser output with the patient's eye is typically a preliminary step for most ophthalmic laser surgery procedures. In general, centration or alignment with the patient's eye is accomplished using the image of the patient's eye and, to some extent, delineating the pupil from the iris. The light intensity or light source direction (e.g., in relation to the eye) may be modified to improve the overall brightness of the imaged eye including both the pupil and iris. Additionally, some displays have a general contrast control to vary the contrast of the entire displayed image to some degree. These techniques may be helpful to delineate the pupil from the iris for lighter eye colors (i.e., lighter iris color). When imaging the eye with a digital camera or other image sensor based device, delineating the pupil from the iris for darker-colored eyes (e.g., brown-colored eyes appear darker that blue-colored eyes) may be difficult and thus, interfere with centration or alignment using the resulting imaged patient's eye. For example, the difference in brightness between a brown-colored iris and a black-colored pupil is much less than the difference in brightness between a blue-colored iris and a black-colored pupil. Changing the light intensity or light source direction or adjusting conventional contrast controls on displays may not sufficiently differentiate the brightness between the brown-colored iris and the black-colored pupil. Additionally, conventional digital video cameras have relatively limited resolution. While images from these conventional digital video cameras may be magnified, the image detail decreased with magnification. Thus, the effective image magnification capabilities of conventional digital video cameras are limited (e.g., for delineating the pupil from the iris for darker-colored eyes).
Accordingly, it is desirable to provide an ophthalmic surgical system and a method of ophthalmic laser surgery that improves centration or alignment with the eye. It is also desirable to provide an ophthalmic surgical system and a method of ophthalmic laser surgery that selectively enhances the contrast of an imaged eye. Additionally, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.